gimbal

What’s the best way to quickly move books from a vast underground archive to the library patrons who want to read them? For the New York Public Library (NYPL), it used to be an elaborate conveyor belt system. But the trouble with those is that the books will fall right off of them on a vertical run. What the NYPL’s gargantuan flagship library on 5th Avenue needed was a train to shuttle the books around. This week, as the majestic Rose Main Reading Room reopens after renovation, the train will leave the station.

From January to August 2016, workers retrofitted the existing conveyor belt infrastructure to support 950 feet of shiny, winding track. ‘Train’ is a bit of a misnomer because the cars travel singly. The double-track system traverses eight floors of library from the underground archive to any of the 11 designated stops. There are 24 book cars at present. Each one can hold about 30 pounds of books and travels at about 75 feet per minute.

In order to move between floors economically, some sections of track are completely vertical. How do the books stay in there? Simple—the cargo hold pivots on a gimbal. Sensors along the track make it easy to keep tabs on the cars, which are separated by a 15-second buffer to avoid collisions and mishaps. Click past the break for a sped-up demonstration. For you purists out there, we’ve also embedded the full, silent, real-time version that clocks in at nearly five minutes.

Warranty? We don’t need no stinking warranty! We’re hackers, and if you have access to a multi-million dollar CNC machine and 3D CAM software, you mill your own headphone replacement parts rather than accept a free handout from a manufacturer.

The headphones in question, Grado SR325s, are hand-built, high-end audiophile headphones, but [Huibert van Egmond] found that the gimbal holding the cups to the headband were loosening and falling out. He replicated the design of the original gimbal in CAM, generated the numeric code, and let his enormous Bridgeport milling machine loose on a big block of aluminum. The part was drilled and tapped on a small knee-mill, cut free from the backing material on a lathe, and bead-blasted to remove milling marks. A quick coat of spray paint – we’d have preferred powder coating or anodization – and the part was ready to go back on the headphones.

Sure, it’s overkill, but when you’ve got the tools, why not? And even a DIY CNC router could probably turn out a part like this – a lot slower, to be sure, but it’s still plausible.

Sometimes, a person has a reason to track a target. A popular way to do this these days is with a camera, a computer, and software to analyze the video. But, that lends itself more to automated systems, like sentries. What if you want to be able to target something by “painting” it with a laser?

That’s exactly what [Jeremy Leaf] wanted to do, and the results are pretty impressive. He was able to track a .06 milliwatt laser at 2 meters. His design does this using three photodiodes in order to determine the position of a laser spot using triangulation.

Once the location of the laser spot has been determined, it can either simply be reported or it can be tracked. Tracking is achieved with a gimbal setup which updates quickly and accurately. Of course, it can only track the laser if the laser has something to be projected upon. If you need to track something in open 3D space, there are alternatives that would be better suited to the task.

What can you do when you have a nice CNC machine, but build beautiful things like this 3-axis gimbal? We covered some of [Gal]’s work before, and he does not subscribe to the idea that hacks should look like hacks. If you’re going to spend hours and hours on something, why not make it better looking than anything you could buy off-the-shelf.

The camera is held stationary with three hollow shaft gimbal motors with low cogging. We weren’t aware of hollow shaft motors, but can think of lots of sensor mounts where such a motor could be used to make very compact and smooth sensor mounts instead of the usual hobby servo configuration. The brains are an off-the-shelf gimbal controller. The gimbal has a DB9 port at the back which handles charging of the internal LiPo batteries as well as giving him a place to input R/C signals for manual control.

The case is made from CNC’d wood and aluminum. There are lots of nice touches. For example, he added two buttons so he could fine tune the pitch of the gimbal. Each button is individually engraved with an up/down arrow.

[Gal] reverse engineered the connector on Garmin action camera he’s using so he can keep it powered, stream video, or add an external mic. Next he built a custom 5.8Ghz video transmitter based on a Boscam module. The transmitter connects to the DB9 charging port on the gimbal.

It’s very cool when someone builds something for themselves that’s far beyond anything they could buy. A few videos of it in operation after the break.

We’ve featured quite a few camera gimbals and steady cams here, but this one stands out. For one, [Daniel Rhyoo] was in his sophomore year when he built it. His 2-axis camera gimbal uses brushless DC motors, and is made out of carbon fiber.

[Daniel] machined the carbon fiber parts on a CNC desktop mill and some hand tools. And he also had to teach himself Solid Works to design it. In his slick DIY guide, he starts off by listing the parts and where to source them from, along with the tools needed. Most gimbals use servos for axis movements, which limits the range and do not provide very smooth motion. Brushless motors overcome these limitations allowing a nice, smooth moving gimbal to be built with a wide range of movement. When [Aleksey Moskalenko] introduced the AlexMos brushless motor controller, [Daniel] ordered it out, and then waited until he could get his hands on the right kind of motors. CAD files for all of the machined parts are available for download (.zip file).

He then goes on to blog his build progress, with ample photos to describe the machining and assembly. He does a couple of nice design choices along the way – like using press-nuts to make assembly and dis-assembly easy, and dismantling one of the motors and replacing its shaft with a custom, longer one instead of using a coupler to extend it. At the end, the result is not only a nice looking, light weight rig, but one that works very well thanks to the motors and controller that he used. Check out the video below to see it in action.

Driving a brushless DC (gimbal) motor can be a pain in the transistors. [Ignas] has written up a nice article not only explaining how to do just this with an Arduino, but also explaining a little bit on how the process works. He uses a L6234 Three Phase Motor Driver, but points out that there are other ways to interface the BLDC motor with the Arduino.

A warning is warranted – this is not for the faint of heart. You can easily destroy your microcontroller if you’re not careful. [Ignas] added several current limiting resistors and capacitors as advised in the application note (PDF warning) to keep things safe.

Everything worked well at high speeds, but for slower speeds the motor was choppy. [Ingus] solved this riddle by changing over to a sine wave to drive the motor. Instead of making the Arduino calculate the wave, he used a look up table.

Be sure to check out his blog for full source and schematics. There is also a video demonstrating just how slow he can make the motor move below.

Holding a video camera while shooting video can lead to finished footage that has some serious shakes. Lucky for us there are some solutions to this problem such as a passive steady cam stabilizer or an active motor-driven gimbal. [Oscar] wanted a smooth-operating brushless motor gimbal but didn’t want to spend the big bucks it costs for a consumer setup so he went out and built his own.

[Oscar] didn’t have a CNC machine or 3D printer to help with his build. He made his gimbal with simple hand tools out of plywood and hardware store bracketry. In his build post, he talks about how it is important to keep the pivoting axes of the gimbal in line with the camera lens and what he did to achieve that goal. The alignment of the axes and the lens ensures that the video is stable while the gimbal adjusts to keep the camera’s angle constant.

[Oscar] purchased the brushless motors and motor controller which included a gyro sensor on a separate PCB board. The gyro is mounted to the camera mount and sends tilt information back to the controller that then moves the brushless motors to keep the camera level. The final project worked out pretty good although [Oscar] admits he still would like to tune the PID settings in the controller a little better. Check out the video after the break where the stabilized camera is compared to one that is not.